Vorkonditionierte konjugierte Gradientenverfahren zur Auflösung großdimensionierter FEM-Systeme

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The mecC-Harboring Region Is a Recombination Hot Spot in Staphylococcus stepanovicii

Introduction Horizontal gene transfer (HGT) is an important driver for resistance- and virulence factor accumulation in pathogenic bacteria such as Staphylococcus aureus. Methods Here, we have investigated the downstream region of the bacterial chromosomal attachment site (attB) for the staphylococcal cassette chromosome mec (SCCmec) element of a commensal mecC- positive Staphylococcus stepanovicii strain (IMT28705; ODD4) with respect to genetic composition and indications of HGT. S. stepanovicii IMT28705 was isolated from a fecal sample of a trapped wild bank vole (Myodes glareolus) during a screening study (National Network on “Rodent-Borne Pathogens”) in Germany. Whole genome sequencing (WGS) of IMT28705 together with the mecC- negative type strain CM7717 was conducted in order to comparatively investigate the genomic region downstream of attB (GenBank accession no. KR732654 and KR732653). Results The bank vole isolate (IMT28705) harbors a mecC gene which shares 99.2% nucleotide (and 98.5% amino acid) sequence identity with mecC of MRSA_LGA251. In addition, the mecC-encoding region harbors the typical blaZ-mecC-mecR1-mecI structure, corresponding with the class E mec complex. While the sequences downstream of attB in both S. stepanovicii isolates (IMT28705 and CM7717) are partitioned by 15 bp direct repeats, further comparison revealed a remarkable low concordance of gene content, indicating a chromosomal “hot spot” for foreign DNA integration and exchange. Conclusion Our data highlight the necessity for further research on transmission routes of resistance encoding factors from the environmental and wildlife resistome

A Look into the Melting Pot: The mecC-Harboring Region Is a Recombination Hot Spot in Staphylococcus stepanovicii

Publisher's version, source: http://dx.doi.org/10.1371/journal.pone.0147150.INTRODUCTION Horizontal gene transfer (HGT) is an important driver for resistance- and virulence factor accumulation in pathogenic bacteria such as Staphylococcus aureus. METHODS Here, we have investigated the downstream region of the bacterial chromosomal attachment site (attB) for the staphylococcal cassette chromosome mec (SCCmec) element of a commensal mecC-positive Staphylococcus stepanovicii strain (IMT28705; ODD4) with respect to genetic composition and indications of HGT. S. stepanovicii IMT28705 was isolated from a fecal sample of a trapped wild bank vole (Myodes glareolus) during a screening study (National Network on “Rodent-Borne Pathogens”) in Germany. Whole genome sequencing (WGS) of IMT28705 together with the mecC-negative type strain CM7717 was conducted in order to comparatively investigate the genomic region downstream of attB (GenBank accession no. KR732654 and KR732653). RESULTS The bank vole isolate (IMT28705) harbors a mecC gene which shares 99.2% nucleotide (and 98.5% amino acid) sequence identity with mecC of MRSA_LGA251. In addition, the mecC-encoding region harbors the typical blaZ-mecC-mecR1-mecI structure, corresponding with the class E mec complex. While the sequences downstream of attB in both S. stepanovicii isolates (IMT28705 and CM7717) are partitioned by 15 bp direct repeats, further comparison revealed a remarkable low concordance of gene content, indicating a chromosomal “hot spot” for foreign DNA integration and exchange. CONCLUSION Our data highlight the necessity for further research on transmission routes of resistance encoding factors from the environmental and wildlife resistome

Genome Sequence Analysis of Clostridium chauvoei Strains of European Origin and Evaluation of Typing Options for Outbreak Investigations

Black quarter caused by Clostridium (C.) chauvoei is an important bacterial disease that affects cattle and sheep with high mortality. A comparative genomics analysis of 64 C. chauvoei strains, most of European origin and a few of non-European and unknown origin, was performed. The pangenome analysis showed limited new gene acquisition for the species. The accessory genome involved prophages and genomic islands, with variations in gene composition observed in a few strains. This limited accessory genome may indicate that the species replicates only in the host or that an active CRISPR/Cas system provides immunity to foreign genetic elements. All strains contained a CRISPR type I-B system and it was confirmed that the unique spacer sequences therein can be used to differentiate strains. Homologous recombination events, which may have contributed to the evolution of this pathogen, were less frequent compared to other related species from the genus. Pangenome single nucleotide polymorphism (SNP) based phylogeny and clustering indicate diverse clusters related to geographical origin. Interestingly the identified SNPs were mostly non-synonymous. The study demonstrates the possibility of the existence of polymorphic populations in one host, based on strain variability observed for strains from the same animal and strains from different animals of one outbreak. The study also demonstrates that new outbreak strains are mostly related to earlier outbreak strains from the same farm/region. This indicates the last common ancestor strain from one farm can be crucial to understand the genetic changes and epidemiology occurring at farm level. Known virulence factors for the species were highly conserved among the strains. Genetic elements involved in Nicotinamide adenine dinucleotide (NAD) precursor synthesis (via nadA, nadB, and nadC metabolic pathway) which are known as potential anti-virulence loci are completely absent in C. chauvoei compared to the partial inactivation in C. septicum. A novel core-genome MLST based typing method was compared to sequence typing based on CRISPR spacers to evaluate the usefulness of the methods for outbreak investigations.Peer Reviewe

Cross-sectional seroprevalence surveys of SARS-CoV-2 antibodies in children in Germany, June 2020 to May 2021

The rate of SARS-CoV-2 infections in children remains unclear due to many asymptomatic cases. We present a study of cross-sectional seroprevalence surveys of anti-SARS-CoV-2 IgG in 10,358 children recruited in paediatric hospitals across Germany from June 2020 to May 2021. Seropositivity increased from 2.0% (95% CI 1.6, 2.5) to 10.8% (95% CI 8.7, 12.9) in March 2021 with little change up to May 2021. Rates increased by migrant background (2.8%, 4.4% and 7.8% for no, one and two parents born outside Germany). Children under three were initially 3.6 (95% CI 2.3, 5.7) times more likely to be seropositive with levels equalising later. The ratio of seropositive cases per recalled infection decreased from 8.6 to 2.8. Since seropositivity exceeds the rate of recalled infections considerably, serologic testing may provide a more valid estimate of infections, which is required to assess both the spread and the risk for severe outcomes of SARS-CoV-2 infections

Use of an Atrial Lead with Very Short Tip-To-Ring Spacing Avoids Oversensing of Far-Field R-Wave

The AVOID-FFS (Avoidance of Far-Field R-wave Sensing) study aimed to investigate whether an atrial lead with a very short tip-to-ring spacing without optimization of pacemaker settings shows equally low incidence of far-field R-wave sensing (FFS) when compared to a conventional atrial lead in combination with optimization of the programming.Patients receiving a dual chamber pacemaker were randomly assigned to receive an atrial lead with a tip-to-ring spacing of 1.1 mm or a lead with a conventional tip-to-ring spacing of 10 mm. Postventricular atrial blanking (PVAB) was programmed to the shortest possible value of 60 ms in the study group, and to an individually determined optimized value in the control group. Atrial sensing threshold was programmed to 0.3 mV in both groups. False positive mode switch caused by FFS was evaluated at one and three months post implantation.A total of 204 patients (121 male; age 73±10 years) were included in the study. False positive mode switch caused by FFS was detected in one (1%) patient of the study group and two (2%) patients of the control group (p = 0.62).The use of an atrial electrode with a very short tip-to-ring spacing avoids inappropriate mode switch caused by FFS without the need for individual PVAB optimization.ClinicalTrials.gov NCT00512915

Size and surface charge of gold nanoparticles determine absorption across intestinal barriers and accumulation in secondary target organs after oral administration

It is of urgent need to identify the exact physico-chemical characteristics which allow maximum uptake and accumulation in secondary target organs of nanoparticulate drug delivery systems after oral ingestion. We administered radiolabelled gold nanoparticles in different sizes (1.4-200 nm) with negative surface charge and 2.8 nm nanoparticles with opposite surface charges by intra-oesophageal instillation into healthy adult female rats. The quantitative amount of the particles in organs, tissues and excrements was measured after 24 h by gamma-spectroscopy. The highest accumulation in secondary organs was mostly found for 1.4 nm particles; the negatively charged particles were accumulated mostly more than positively charged particles. Importantly, 18 nm particles show a higher accumulation in brain and heart compared to other sized particles. No general rule accumulation can be made so far. Therefore, specialized drug delivery systems via the oral route have to be individually designed, depending on the respective target organ

The GimA Locus of Extraintestinal Pathogenic E. coli: Does Reductive Evolution Correlate with Habitat and Pathotype?

IbeA (invasion of brain endothelium), which is located on a genomic island termed GimA, is involved in the pathogenesis of several extraintestinal pathogenic E. coli (ExPEC) pathotypes, including newborn meningitic E. coli (NMEC) and avian pathogenic E. coli (APEC). To unravel the phylogeny of GimA and to investigate its island character, the putative insertion locus of GimA was determined via Long Range PCR and DNA-DNA hybridization in 410 E. coli isolates, including APEC, NMEC, uropathogenic (UPEC), septicemia-associated E. coli (SEPEC), and human and animal fecal isolates as well as in 72 strains of the E. coli reference (ECOR) collection. In addition to a complete GimA (∼20.3 kb) and a locus lacking GimA we found a third pattern containing a 342 bp remnant of GimA in this strain collection. The presence of GimA was almost exclusively detected in strains belonging to phylogenetic group B2. In addition, the complete GimA was significantly more frequent in APEC and NMEC strains while the GimA remnant showed a higher association with UPEC strains. A detailed analysis of the ibeA sequences revealed the phylogeny of this gene to be consistent with that obtained by Multi Locus Sequence Typing of the strains. Although common criteria for genomic islands are partially fulfilled, GimA rather seems to be an ancestral part of phylogenetic group B2, and it would therefore be more appropriate to term this genomic region GimA locus instead of genomic island. The existence of two other patterns reflects a genomic rearrangement in a reductive evolution-like manner

Untersuchung der Bildung von Defekten und der Diffusionskinetik auf III-V-Halbleiteroberflächen mit Hilfe der Hochtemperatur-Rastertunnelmikroskopie

The kinetic of formation and diffusion of defects in (110) cleavage surfaces of III-V semiconductors is investigated by high temperature Scanning tunneling microscopy as a function of temperature and dopant concentration. One point of main interest is the formation of phosphorus vacancies. It is shown that the measured rate of formation is given by the rate of phosphorus adatom diffusion. The diffusion of the adatoms is one dimensional along the [$\overline{1}$10] direction. The activation energy for adatom diffusion is determined to E$_{\alpha}$ = (0,47 ± 0,05) eV for a 1,1 - 10$^{18}$ cm$^{-3}$ doped InP(110) surface. With an increasing dopant concentration of the surfaces the rate of formation is increasing. This means the adatom diffusion depends an the Fermi niveau. Additionally the vacancies can diffuse into the bulk of the crystal. Because of the electrical charge of the vacancies crystals form a layer beyond the surface with semiinsulating properties and p-type conductivity. The activation energy for indiffusion is determined to E$_{d}$ = (0,57 ± 0,12) eV and the diffusion coefficent to D$_{0}$ = 10$^{-7\pm 3}$ cm$^{2}$ s$^{-1}$. The indiffusion is influenced by Coulomb interaction between charged vacancies and dopant atoms. For measuring intensity and range of this interaction the screening length is measured. In the bulk the screening length seems to be lower than the theoretical expected because of many body effects. This is shown using a Monte Carlo simulation. The corrected value is increasing exponentially wich increasing Fermi niveau whereas the screening length at the surface R$_{S}$ = (0,9 ± 0,3) nm is independent from Fermi niveau, concentration of dopant atoms and semiconductor material. This is in agreement wich specific surface contributions to screening leading to a two-dimensional screening

Berührungslose Drahtvorschubgeschwindigkeitsmessung und Einsatz einer robusten digitalen Regelung beim Schweißen mit abschmelzender Endloselektrode

Im Bericht werden die Ergebnisse des DFG-Forschungsprojektes unter den DFG-Geschäftszeichen MA1391/17-3 und NE615/1-1 ergänzend zum Abschlussbericht des Projektes ausführlich dargestellt. Inhalt der Forschung war die Weiterentwicklung eines optischen Messverfahrens zur Bestimmung der Drahtvorschubgeschwindigkeit beim MSG-Schweißen mit Integration eines PI-Reglers zur Steuerung der Drahtvorschubeinrichtung. Die in dem Vorgängerprojekt (DFG-Gz. MA1391/17-1) entwickelten schnellen Wavelet-Algorithmen, die eine Auswertung der Videoaufzeichnung in Echtzeit erlauben, wurden weiterentwickelt. Es erfolgte eine große Zahl von Versuchen mit Drähten aus vier Werkstoffgruppen (Aluminium, Kupfer, Stahl und Nickel), unterschiedlichen Geschwindigkeiten und Formen der Störung des Drahtlaufes. Simuliert wurden weiterhin unterschiedlichen Formen der Verschmutzungen des Videosignals. Die Einsatzfähigkeit und Robustheit des Mess- und Regelalgorithmus unter diesen industrienahen Bedingungen konnte nachgewiesen werden.In this report the results of the DFG project MA1391/17-3 and NE615/1-1 are summarized and explained in details. The research topic is the further development of an optical method of measuring the speed of welding wire feed for MIG welding. A common PI-Controller was used for regulating the wire feed speed. The fast wavelet algorithms developed in the preceding DFG-Project MA1391/17-1, which allow the analysis of the video camera signal in the real time, have been perfected. The report includes the description and summary of a lot of practical tests with different wire materials (aluminium, steel, cupper and nickel), different feed speeds and different kinds of free wire run perturbations. Several filters simulating the lens pollutions have been tested. The applicability and robustness of measuring and controlling under near to industry conditions have been proved